> > http://pastebin.com/WVkbY3s9 is main xwiki.hbm.xml
> > I pasted it into http://xpath.me/
> >
> > And those queries return some interesting results, that i don;t know mapped to what.
> >
> >>> //*[@length>2000][@type="text"] << this i hope just create a BLOB, and hopefully not used it for grouping an such
> >>> //*[@length>2000][@type!="text"]" << but this... what it might be...

Could u have a look ?
There are a bunch of Java types, that are probably too reach for FB dialect and ruins all this.

There is an outdated article, however it highlights end result, not the changes required and reasoning.
http://blog.progs.be/57/xwiki-installation-on-jboss-using-firebird


BTW, i wonder if hibernate dialect can forbid using certain datatypes for GROUP By, etc. Not that it is good thing to do with BLOBS, but if the dialect would do such mapping according to string length, then it should try to prevent exposure of BLOB limitations in FB.

> The generator class is 'assigned', which means that the application

Thanks for explanation.